Thermoanalytical Characterization of the Hydration States of Risedronate

摘要

Risedronate, the active pharmaceutical ingredient in Actonel, is manufactured as the hemi-pentahydrate. In addition to the hemi-pentahydrate, monohydrate and anhydrate forms of the drug have been isolated. Each of these hydrate forms displayed a unique thermoanaytical signature by both TGA and DSC. The appearance of the TGA and DSC thermal curves for the hemi-pentahydrate form is highly dependent upon experimental parameters such as scan rate and sample pan venting. Most of this dependence can be explained by the channel nature of a portion of the water of hydration of the hemi-pentahydrate and the fact that under some conditions, a conversion from hemi-pentahydrate to monohydrate occurred during the thermoanalytical experiment.